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DevelopersStartHere
Notes I hope are useful to anyone wanting to hack on Sloppy
DEVELOPER NOTES
In addition to the Java Doc this short note should help you get into the code.
Although Sloppy now looks like a desktop application, it was first developed as a server application: it would listen for HTTP requests on a particular port for any number of users.
Sloppy still works this way. If you're running Sloppy on your machine, anyone else on the network can connect to your instance of Sloppy and see a site slowed down. However, this doesn't really make much sense anymore, and it's not the direction the code is going in.
To understand the code, start with SloppyServer. This class starts listening on a port and hands off each request to an instance of SlowProxyThread.
SlowProxyThread is the go-between for reading from the web browser, calling the web server, reading from the web server and passing the data back to the web client.
This is where the bandwidth limited happens. Just before writing data back to the web browser, SlowProxyThread calculates the pause required to simulate a particular bandwidth setting. I.e., the thinking is "I've sent so-many bytes in the last so-many seconds; if I was a 56k modem, that would have really taken X seconds, so I need to pause before I send that data on."
The class Bottleneck implements this thinking. To keep track of the bandwidth usage, there's a class called Usage. Note that Bandwidth keeps a hash of Usage objects -- one per client, because (remember) Sloppy is a multi-user server behind the scenes.
[BTW, previous versions of Sloppy just connected the output from the browser to the input of the web server, and the output from the server to the input of the web browser -- as two separate threads. This was sort of elegant, but because it used java.net.Socket it didn't work with proxies. As of version 1.1 Sloppy uses URLConnection.]
The GUI side of Sloppy is set up by MatisseGUI (originally: SloppyGUI). This just reads and writes the Configuration object -- the Configuration being the port to listen on, the Bandwidth to simulate... etc.
Sloppy.java is the main class that kicks all this off. It decides if the user wants to start up with or without a GUI and reads the Configuration (either taking the defaults, reading a properties file from disk, or reading the properties file from a Java Web Start "muffin").
Sloppy produces a number of messages (debugging, errors). When running with a GUI, these messages need to go to pop-up windows; when running without a GUI, the messages go to the console. The interface UserInterface.java defines the types of messages that Sloppy can produce. MatisseGUI implements the UserInterface where messages are sent to pop-up windows. ConsoleLogger implements the UserInterface where messages are sent to the console. You can ask the Configuration object to give you the current UserInterface so your messages will go to the right place. In this respect, the Configuration objects acts as the meeting point between the GUI and the SloppyServer object.
The final class is ReleaseInfo, which is a singleton to tell you what version of Sloppy is running and what the copyright notice is. The build number is held in build.properties, and I use an ANT script to increment the build number after each build of the system.
JUNIT
There are a small number of JUnit tests with Sloppy. See http://www.junit.org for information about JUnit.
COMPILATION
To compile Sloppy you will need junit.jar (from junit.org, version 4.3), jnlp.jar (from the Web Start install, or from your JDK in jre/javaws/javaws.jar which for the Mac is /Applications/Utilities/Java/Java\ Web\ Start.app/Contents/MacOS/javaws.jar or /System/Library/Frameworks/JavaVM.framework/Versions/1.5.0/Home/lib/javaws.jar) and the swing-layout JAR that ships with netbeans (and is also available in sloppy/lib).
JAVA WEB START DEPLOYMENT
Because Sloppy access the network it needs permission to do so, and as such we need to sign it to make the prompt for this less scary to end users. The command to sign the JAR is: ant -f etc/build.xml -Dkey.alias=key-store-alias -Dkey.password=passwordhere Right now only RD is signing the jar for public deployment. If you want to sign your own copy, take a look at the details over at http://www.dallaway.com/acad/webstart/
RUNNING A LOCAL COPY
Launch your copy of Sloppy with: javaws local.jnlp You'll want to adjust the codebase in local.jnlp for your machine, but other than that, it ought to work.
You can also run a non-GUI, debug version, that's a little more chatty in the console window. On a Mac the command is:
java -cp sloppy.jar:/System/Library/Frameworks/JavaVM.framework/Versions/1.5.0/Home/lib/javaws.jar com.dallaway.sloppy.Sloppy -gui -debug -site http://wherever-you-want-to-test.com/
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